// Copyright (C) 2008 Victor Marzo
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;

namespace NForth
{
	public class Parser
	{
		private static string current_line = "";
		
		public static string Buffer
		{
			get { return current_line; }
			set { current_line = value; }
		}
		
		public static bool EndOfLine
		{
			get { return current_line == ""; }
		}
		
		private static int IndexOfFirstSpace()
		{
			int index_of_space = current_line.IndexOf(' ');
			int index_of_tab = current_line.IndexOf('\t');
			
			if(index_of_space >= 0 && (index_of_space < index_of_tab || index_of_tab == -1))
				return index_of_space;
			else if(index_of_tab >= 0)
				return index_of_tab;
			else
				return -1;
		}
		
		public static void NextLine()
		{
			current_line = Console.ReadLine();
			if(current_line == null)
			{
				current_line = "";
				throw new EndOfStreamException();
			}
		}

		public static string NextWord()
		{
			if(current_line == "")
				NextLine();

			int index_of_space = IndexOfFirstSpace();
			if(index_of_space < 0)
			{
				string word = current_line;
				current_line = "";
				return word;
			}
			else
			{
				string word = current_line.Substring(0, index_of_space);
				current_line = current_line.Substring(index_of_space + 1);
				return word;
			}
		}
		
		public static string ReadUntil(string delimiter)
		{
			string l;
			if(current_line.Contains(delimiter))
			{
				int index = current_line.IndexOf(delimiter);
				l = current_line.Substring(0, index);
				current_line = current_line.Substring(index + 1);
			}
			else
			{
				l = current_line;
				NextLine();
				l += ReadUntil(delimiter);
			}
			
			return l;
		}
	}
}
